The plants represented here have a POWO (Plants of the World Online) Status of Tree, Shrub, Shrub or Tree, SubShrub or Caudex Tree – but what’s the difference?

The primary difference between a shrub and a tree lies in their structure and size. Trees typically have a single, dominant trunk that supports a distinct crown, while shrubs are characterized by multiple stems branching from or near the ground, often forming a more rounded, bushy shape. Shrubs are also generally smaller than trees, with most reaching a maximum height of around 6-10 meters (20-33 feet). 

Here’s a more detailed breakdown:

• Trunk:Trees generally have a single, main trunk that can be quite thick, while shrubs typically have multiple stems emerging from the base. 
• Height:Trees can grow much taller than shrubs. While there’s no strict height limit, trees are generally taller than 6-10 meters, whereas shrubs are usually smaller. 
• Branching:Trees tend to have branches that start higher up on the trunk, while shrub branches often originate closer to the ground. 
• Shape:Trees typically have a more upright and defined shape, while shrubs tend to be more rounded and bushy. 

A Caudex Tree is characterized by having a thick, woody, often swollen base or trunk called a “caudex,” which stores water and nutrients. This adaptation allows the tree to survive in dry or harsh environments, often by accumulating resources during periods of rainfall. The caudex acts as a reservoir, helping the plant to endure droughts.

A subshrub is a plant that is intermediate between an herb and a shrub and slightly woody only at the base; a perennial plant woody only at the base.

While these are general guidelines, it’s important to note that there can be some overlap, and some plants can be classified as either trees or shrubs depending on environmental conditions and pruning practices. For example, a plant that is normally considered a shrub may grow into a single-trunked tree if pruned and given sufficient space and sunlight.